The present invention relates to an arrangement of a working doctor blade on an ink-coated roller. The doctor blade is set against the roller at a negative angle. The roller has a structured surface with endless grooves.
A short inking system for offset inks, having an ink feed and a doctor blade arrangement with a negative working doctor blade for an ink metering roller, is known from DE 37 04 433 A1.
DE 42 13 662 C2 shows a chamber doctor blade, wherein the working doctor blade is placed against the surface of an ink-coated roller at a negative setting angle of approximately 40xc2x0. The surface of this roller is structured in the form of small cups.
The present invention was the object of providing an inking system with at least one working doctor blade. This working doctor blade is placed at a negative angle against a roller with a structured surface. The result of this is that it is possible to prevent, to the greatest extent, undesired ink deposits of printing ink on the outer surface of the working doctor blade facing the roller.
In accordance with the present invention, this object is attained by the provision of a working doctor blade that is placed at a negative angle of between 0xc2x0 and 35xc2x0 against the surface of an ink-coated roller. The roller has a structured surface which includes endless or helix-like grooves at an angle of inclination or a lead angle of 0xc2x0 to plus/minus 20xc2x0.
The advantages which can be achieved by the present invention reside, in particular in that no unintended formation of ink droplets will occur on the outer surface of doctor blades, in particular working doctor blades. It is thus avoided that, starting at a defined size, the ink droplets are released from the outer surface of the working doctor blade and reach the inking system roller which, follows, which in the end, results in excessive local inking of the printed sheet. This also applies in connection with the use of highly viscous ink of a viscosity of greater than 2 Paxc3x97s, in particular starting at 10 Paxc3x97s.